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Home >> GMC >> 2000 >> Jimmy 4D Utility, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 4.3L >> Self-Diagnostic System >> Malfunction Indicator Light Circuit Check
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Malfunction Indicator Light Circuit Check

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Turn engine off for 15 seconds. Turn ignition on, with engine off. If Malfunction Indicator Light (MIL) illuminates, go to next step. If MIL does not illuminate, go to step  5.
  3. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, see appropriate TROUBLE SHOOTING - NO CODES article. If MIL does not turn on and off as commanded, go to next step.
  4. Turn ignition off. Disconnect VCM harness connector. See WIRING DIAGRAMS article. Turn ignition on. If MIL does not illuminate, go to step  19. If MIL illuminates, go to step  13.
  5. Check for open gauge, battery or ignition feed fuses. If any fuses are open, go to step  14. If all fuses are okay, go to next step.
  6. Turn ignition off. Disconnect VCM harness connector. See WIRING DIAGRAMS article. Turn ignition on, with engine off. Using a fused jumper wire connected to ground, probe MIL control circuit at VCM harness connector C4. If MIL illuminates, go to step  16. If MIL does not illuminate, go to next step.
  7. Check fused jumper wire. If fuse is open, go to step  15. If fuse is okay, go to next step.
  8. Check for open in MIL control circuit. Repair as necessary. After repairs, go to step  20. If circuit is okay, go to next step.
  9. Check for open in circuit between MIL and GAUGE fuse (10-amp). Repair as necessary. After repairs, go to step  20. If circuit is okay, go to next step.
  10. Check for faulty MIL bulb. Repair as necessary. After repairs, go to step  20. If MIL bulb is okay, go to next step.
  11. Check harness connections at instrument cluster. Repair as necessary. After repairs, go to step  20. If harness connections are okay, go to next step.
  12. Replace instrument cluster. After repairs, go to step  20.
  13. Repair short to ground in MIL control circuit. After repairs, go to step  20.
  14. Check for a short to ground in circuit associated with circuit of open fuse. Repair as necessary. Replace open fuse. After repairs, go to step  20.
  15. Repair short to voltage in MIL control circuit between MIL and VCM. After repairs, go to step  20.
  16. Disconnect VCM harness connector. See WIRING DIAGRAMS article. Using a test light connected to ground, probe both VCM ground circuits at VCM harness connector. If test light illuminates at both circuits, go to step  18. If test light does not illuminate at both circuits, go to next step.
  17. Repair open in VCM ground circuit. After repairs, go to step  20.
  18. Check for poor connections at VCM. Repair as necessary. After repairs, go to step  20. If connections are okay, go to next step.
  19. Replace VCM. Perform appropriate relearn procedures for VCM, CKP and anti-theft systems. After repairs, go to next step.
  20. Turn ignition off for 15 seconds. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step  2.
  21. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, system is okay. If MIL does not turn on and off as commanded, go to step  2.
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